HST/STIS Images of GRB 000301C


On the left in the above image is the April 2000 STIS 50ccd image of GRB 000301C, on the right February 2001 50ccd image. The field of view in each case is approximately 3."5 from East to West (left to right). The images have been drizzled onto an output grid with pixels one-half the size of the original STIS pixels, or about 0."025 on a side. The OT of GRB 000301C is clearly visible in the south-east corner of the image of the April 2000 image. It is no longer visible in the February 2001 image.

The field of GRB 000301c was reobserved by the Hubble Space Telescope using the STIS camera in open (50CCD) mode on the 25 Feb 2001, or nearly one year after outburst. Twelve dithered exposures were combined to produce a final image with an exposure time of 7031s. No source is immediately visible at the position of the GRB. However, when the image is convolved with gaussians or boxcars with characteristic sizes from that of the PSF, 0."08, to 0."2, an extended object appears to be visible under the position of the GRB and to its NE. Although extended light from both a nearby bright star, and the larger galaxy to the NW of the GRB make an exact determination of the significance of this object difficult, we believe this is approximately a 3-4 sigma detection. The probable host has an estimated magnitude of R = 28.0 +/- 0.3. This magnitude is just consistent with the estimates of an underlying host from our earlier imaging, GCN 627 and 701. It is, furthermore, about two magnitudes brighter than we would expect the OT to have been at this time, had it continued to decline with a temporal power-law steeper than -2 (c.f. GCN 701 and Rhoads and Fruchter, ApJ 2001, 546, 177). If this is indeed a detection of a host, then in all cases where we have obtained a deep HST image and an OT is well localized (to ~0."1), a host has been found under the GRB. However, again, due to the scattered and extended light in this region of the image, the detection must be considered tentative. This result has been reported as GCN ...


The image above left shows the same field of view as seen in the first figure, but the 25 February 2001 mage has been convolved with a Gaussian the size of the core of the PSF (FWHM 0."08). A region of emission is now more clearly visible at the position of the OT, and is marked with a green arrow. On the right we show an expanded field of view (~14"). Additionally a somewhat larger convolution, a Gaussian of FWHM ~0."16, has been been applied. The probable host is near the center of the field and is marked with an arrow. The bright object at the center right is a foreground star.